// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* fs/inotify_user.c - inotify support for userspace
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*
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* Authors:
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* John McCutchan <ttb@tentacle.dhs.org>
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* Robert Love <rml@novell.com>
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*
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* Copyright (C) 2005 John McCutchan
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* Copyright 2006 Hewlett-Packard Development Company, L.P.
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*
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* Copyright (C) 2009 Eric Paris <Red Hat Inc>
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* inotify was largely rewriten to make use of the fsnotify infrastructure
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*/
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#include <linux/dcache.h> /* d_unlinked */
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#include <linux/fs.h> /* struct inode */
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#include <linux/fsnotify_backend.h>
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#include <linux/inotify.h>
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#include <linux/path.h> /* struct path */
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#include <linux/slab.h> /* kmem_* */
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#include <linux/types.h>
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#include <linux/sched.h>
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#include <linux/sched/user.h>
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#include <linux/sched/mm.h>
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#include "inotify.h"
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/*
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* Check if 2 events contain the same information.
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*/
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static bool event_compare(struct fsnotify_event *old_fsn,
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struct fsnotify_event *new_fsn)
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{
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struct inotify_event_info *old, *new;
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old = INOTIFY_E(old_fsn);
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new = INOTIFY_E(new_fsn);
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if (old->mask & FS_IN_IGNORED)
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return false;
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if ((old->mask == new->mask) &&
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(old->wd == new->wd) &&
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(old->name_len == new->name_len) &&
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(!old->name_len || !strcmp(old->name, new->name)))
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return true;
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return false;
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}
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static int inotify_merge(struct list_head *list,
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struct fsnotify_event *event)
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{
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struct fsnotify_event *last_event;
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last_event = list_entry(list->prev, struct fsnotify_event, list);
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return event_compare(last_event, event);
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}
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int inotify_handle_inode_event(struct fsnotify_mark *inode_mark, u32 mask,
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struct inode *inode, struct inode *dir,
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const struct qstr *name, u32 cookie)
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{
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struct inotify_inode_mark *i_mark;
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struct inotify_event_info *event;
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struct fsnotify_event *fsn_event;
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struct fsnotify_group *group = inode_mark->group;
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int ret;
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int len = 0;
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int alloc_len = sizeof(struct inotify_event_info);
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struct mem_cgroup *old_memcg;
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if (name) {
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len = name->len;
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alloc_len += len + 1;
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}
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pr_debug("%s: group=%p mark=%p mask=%x\n", __func__, group, inode_mark,
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mask);
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i_mark = container_of(inode_mark, struct inotify_inode_mark,
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fsn_mark);
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/*
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* Whoever is interested in the event, pays for the allocation. Do not
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* trigger OOM killer in the target monitoring memcg as it may have
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* security repercussion.
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*/
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old_memcg = set_active_memcg(group->memcg);
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event = kmalloc(alloc_len, GFP_KERNEL_ACCOUNT | __GFP_RETRY_MAYFAIL);
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set_active_memcg(old_memcg);
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if (unlikely(!event)) {
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/*
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* Treat lost event due to ENOMEM the same way as queue
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* overflow to let userspace know event was lost.
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*/
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fsnotify_queue_overflow(group);
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return -ENOMEM;
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}
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/*
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* We now report FS_ISDIR flag with MOVE_SELF and DELETE_SELF events
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* for fanotify. inotify never reported IN_ISDIR with those events.
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* It looks like an oversight, but to avoid the risk of breaking
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* existing inotify programs, mask the flag out from those events.
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*/
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if (mask & (IN_MOVE_SELF | IN_DELETE_SELF))
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mask &= ~IN_ISDIR;
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fsn_event = &event->fse;
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fsnotify_init_event(fsn_event, 0);
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event->mask = mask;
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event->wd = i_mark->wd;
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event->sync_cookie = cookie;
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event->name_len = len;
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if (len)
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strcpy(event->name, name->name);
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ret = fsnotify_add_event(group, fsn_event, inotify_merge);
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if (ret) {
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/* Our event wasn't used in the end. Free it. */
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fsnotify_destroy_event(group, fsn_event);
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}
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if (inode_mark->mask & IN_ONESHOT)
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fsnotify_destroy_mark(inode_mark, group);
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return 0;
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}
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static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
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{
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inotify_ignored_and_remove_idr(fsn_mark, group);
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}
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/*
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* This is NEVER supposed to be called. Inotify marks should either have been
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* removed from the idr when the watch was removed or in the
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* fsnotify_destroy_mark_by_group() call when the inotify instance was being
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* torn down. This is only called if the idr is about to be freed but there
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* are still marks in it.
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*/
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static int idr_callback(int id, void *p, void *data)
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{
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struct fsnotify_mark *fsn_mark;
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struct inotify_inode_mark *i_mark;
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static bool warned = false;
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if (warned)
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return 0;
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warned = true;
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fsn_mark = p;
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i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
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WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
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"idr. Probably leaking memory\n", id, p, data);
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/*
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* I'm taking the liberty of assuming that the mark in question is a
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* valid address and I'm dereferencing it. This might help to figure
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* out why we got here and the panic is no worse than the original
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* BUG() that was here.
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*/
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if (fsn_mark)
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printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
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fsn_mark->group, i_mark->wd);
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return 0;
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}
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static void inotify_free_group_priv(struct fsnotify_group *group)
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{
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/* ideally the idr is empty and we won't hit the BUG in the callback */
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idr_for_each(&group->inotify_data.idr, idr_callback, group);
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idr_destroy(&group->inotify_data.idr);
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if (group->inotify_data.ucounts)
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dec_inotify_instances(group->inotify_data.ucounts);
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}
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static void inotify_free_event(struct fsnotify_event *fsn_event)
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{
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kfree(INOTIFY_E(fsn_event));
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}
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/* ding dong the mark is dead */
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static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
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{
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struct inotify_inode_mark *i_mark;
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i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
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kmem_cache_free(inotify_inode_mark_cachep, i_mark);
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}
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const struct fsnotify_ops inotify_fsnotify_ops = {
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.handle_inode_event = inotify_handle_inode_event,
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.free_group_priv = inotify_free_group_priv,
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.free_event = inotify_free_event,
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.freeing_mark = inotify_freeing_mark,
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.free_mark = inotify_free_mark,
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};
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